Air-conditioning system

ABSTRACT

An air-conditioning system includes an air conditioner, a heat source device, and a controller. In a case where an indoor temperature is a setting value, the controller performs a first adjustment operation including: transmitting a switching signal to the heat source device to instruct the heat source device to switch a setting water temperature to a first setting water temperature; and adjusting a temperature difference of heat-exchange water to a target water temperature difference. In a case where the indoor temperature is not the setting value, the controller performs a second adjustment operation including: transmitting a switching signal to the heat source device to instruct the heat source device to switch the setting water temperature to a second setting water temperature; and adjusting an air supply temperature of air-conditioning air to a setting air supply temperature.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an indoor air-conditioning system, and mainly to a system that performs adjustment of indoor temperature.

2. Description of the Related Art

There have been air-conditioning systems that utilize water for use in heat exchange (hereinafter, “heat-exchange water”) as air-conditioning energy. Japanese Laid-Open Patent Application Publication No. 2013-53836 discloses one example of such an air-conditioning system. The air-conditioning system includes: a heat source device that adjusts the temperature of the heat-exchange water; an air conditioner that performs indoor air conditioning by adjusting an air supply temperature of air for use in air conditioning (hereinafter, “air-conditioning air”) with use of a heat exchanger through which the heat-exchange water flows; and a water circulating apparatus that circulates the heat-exchange water through the air conditioner and the heat source device. The heat-exchange water absorbs heat from, or releases heat to, the air-conditioning air in the heat exchanger. If the temperature of the heat-exchange water deviates from its setting water temperature as a result of the absorption or release of the heat, then the heat source device cools down or heats up the heat-exchange water, thereby bringing the temperature of the heat-exchange water to the setting water temperature.

In a case where the heat-exchange water is cold water, the higher the setting water temperature, the less the amount of energy necessary for cooling down the heat-exchange water to the setting water temperature, i.e., the less the amount of energy consumed by the heat source device for cooling down the heat-exchange water to the setting water temperature. On the other hand, in a case where the heat-exchange water is hot water, the lower the setting water temperature, the less the amount of energy necessary for heating up the heat-exchange water to the setting water temperature, i.e., the less the amount of energy consumed by the heat source device for heating up the heat-exchange water to the setting water temperature. That is, the setting water temperature that requires a less amount of energy to be consumed by the heat source device is different between the case where the heat-exchange water is cold water and the case where the heat-exchange water is hot water. However, the setting water temperature is always fixed. Therefore, while the indoor temperature is stable within a preset indoor temperature allowable range, or during an intermediate period in which the air-conditioning load is small, i.e., during a period other than a summer period and a winter period within one year, heating up or cooling down the heat-exchange water to the setting water temperature results in wasteful consumption of energy. In addition, periods in which the air-conditioning load does not become highest take up most of the year. Accordingly, a large amount of energy of the heat source device is consumed wastefully.

An object of the present invention is to provide an air-conditioning system capable of reducing such wasteful consumption of the energy of the heat source device.

SUMMARY OF THE INVENTION

An air-conditioning system according to a first aspect of the present invention includes: an air conditioner configured to adjust an air supply temperature of air-conditioning air by using heat-exchange water, and supply the air-conditioning air to indoors; a heat source device configured to adjust a temperature of the heat-exchange water, and selectively switch a setting water temperature of the heat-exchange water, to which the temperature of the heat-exchange water is to be adjusted, between a first setting water temperature preset corresponding to low exergy and a second setting water temperature preset corresponding to high exergy; and a controller configured to transmit a switching signal to the heat source device to instruct the heat source device regarding which one of the first setting water temperature and the second setting water temperature the setting water temperature of the heat-exchange water is to be switched to, and perform loading of a preset indoor temperature allowable range, a target water temperature difference, a setting value of an indoor temperature, and a setting air supply temperature. The air conditioner includes: a heat exchanger, through which the heat-exchange water flows; and a water regulating valve configured to increase and decrease an amount of heat-exchange water flowing through the heat exchanger to adjust a temperature difference between a temperature of the heat-exchange water at an inlet side of the heat exchanger and a temperature of the heat-exchange water at an outlet side of the heat exchanger and adjust the air supply temperature of the air-conditioning air. The controller performs a first adjustment operation in a case where the indoor temperature is the setting value, the first adjustment operation including: transmitting a switching signal to the heat source device to instruct the heat source device to switch the setting water temperature of the heat-exchange water to the first setting water temperature; and operating and controlling the water regulating valve to adjust the temperature difference between the temperature of the heat-exchange water at the inlet side of the heat exchanger and the temperature of the heat-exchange water at the outlet side of the heat exchanger to a target water temperature difference. The controller performs a second adjustment operation in a case where the indoor temperature is not the setting value, the second adjustment operation including: transmitting a switching signal to the heat source device to instruct the heat source device to switch the setting water temperature of the heat-exchange water to the second setting water temperature; and operating and controlling the water regulating valve to adjust the air supply temperature of the air-conditioning air to the setting air supply temperature.

In the first aspect of the present invention, the term “exergy” refers to “maximum energy extractable from a system until the system achieves equilibrium with its environment during a process that brings the system into equilibrium with its environment”. The term “low exergy” means that the amount of extractable energy is small. The term “high exergy” means that the amount of extractable energy is large. Therefore, specifically, the “first setting water temperature preset corresponding to low exergy” and the “second setting water temperature preset corresponding to high exergy” mean that in a case where the heat-exchange water is cold water, the first setting water temperature is higher than the second setting water temperature, because, in this case, the higher setting water temperature requires less energy for cooling down the heat-exchange water to the setting water temperature, and also mean that in a case where the heat-exchange water is hot water, the first setting water temperature is lower than the second setting water temperature, because, in this case, the lower setting water temperature requires less energy for heating up the heat-exchange water to the setting water temperature. In this manner, the first and second setting water temperatures in a case where the heat-exchange water is cold water are made different from the first and second setting water temperatures in a case where the heat-exchange water is hot water, and thereby wasteful energy consumption of the heat source device can be reduced.

In a case where the indoor temperature is the setting value, the temperature difference between the temperature of the heat-exchange water at the inlet side of the heat exchanger and the temperature of the heat-exchange water at the outlet side of the heat exchanger is adjusted to the target water temperature difference. In this manner, quick cooling, quick heating, or the like of the heat-exchange water can be prevented, and thereby wasteful energy consumption can be reduced.

In a case where the indoor temperature is not the setting value, the temperature to which the temperature of the heat-exchange water is to be adjusted is set to the second setting water temperature in preparation for an increase in air-conditioning load. In this manner, while keeping a variation in the indoor temperature to a minimum, cooling or heating is performed quickly until the air supply temperature of the air-conditioning air becomes the setting air supply temperature. This makes it possible to perform air conditioning with excellent stability and comfortableness.

In a second aspect of the present invention, in a case where the indoor temperature deviates from the indoor temperature allowable range, the controller outputs a switching signal to the heat source device to instruct the heat source device to switch the setting water temperature of the heat-exchange water to the second setting water temperature, and when a setting elapsed time has passed after the indoor temperature reaches the setting value, if a state where the indoor temperature is in the indoor temperature allowable range is maintained, the controller outputs a switching signal to the heat source device to instruct the heat source device to switch the setting water temperature of the heat-exchange water to the first setting water temperature. According to the second aspect of the present invention, if the indoor temperature is still in the indoor temperature allowable range after the setting elapsed time has passed, it can be considered that there is a small or no variation in the air-conditioning load. Accordingly, the temperature to which the temperature of the heat-exchange water is to be adjusted is set to the first setting water temperature corresponding to low exergy. In this manner, a phenomenon called chattering, in which the setting water temperature of the heat-exchange water is switched frequently, can be prevented while the heat source device is in operation. This makes it possible to improve the reliability and stability of the heat source device.

Moreover, by setting the indoor temperature allowable range, overcooling and overheating caused by the switching of the setting water temperature of the heat-exchange water can be reduced while the heat source device is in operation. Therefore, overshoot and undershoot of the indoor temperature (i.e., excessive deviation of the indoor temperature from a predetermined setting temperature) can be readily suppressed, and air conditioning with excellent stability and comfortableness can be performed.

In a third aspect of the present invention, in a case where the heat-exchange water is cold water, the first setting water temperature is set to 9 to 11° C., and the second setting water temperature is set to 6 to 8° C., and in a case where the heat-exchange water is hot water, the first setting water temperature is set to 34 to 36° C., the second setting water temperature is set to 39 to 41° C., and the target water temperature difference is set to 9 to 11° C. The inventors of the present invention have found out that, in a case where the heat-exchange water is cold water, the amount of energy consumed by the heat source device can be effectively reduced by setting the first setting water temperature to 9 to 11° C. and setting the second setting water temperature to 6 to 8° C. as in the third aspect of the present invention. The inventors have also found out that, in a case where the heat-exchange water is hot water, the same advantageous effect can be obtained by setting the first setting water temperature to 34 to 36° C. and setting the second setting water temperature to 39 to 41° C.

In a fourth aspect of the present invention, the air-conditioning system includes a water circulating apparatus configured to circulate the heat-exchange water between the heat source device and the heat exchanger. The water circulating apparatus includes: a cold water circulation passage, through which the heat-exchange water that is cold water flows; a hot water circulation passage, through which the heat-exchange water that is hot water flows; and a water circulation passage switching mechanism configured to connect the cold water circulation passage, the hot water circulation passage, and the heat exchanger, and switch the heat-exchange water flowing through the heat exchanger between the cold water and the hot water. According to the fourth aspect of the present invention, cooling and heating of indoor air can be switched by means of one heat exchanger. Accordingly, power for air feeding can be reduced compared to a case where two heat exchangers, i.e., a heat exchanger dedicated for cooling and a heat exchanger dedicated for heating, are installed, and thereby energy saving can be realized. Moreover, the air conditioner can be made compact. Furthermore, during a period in which the air-conditioning load is small, such as an intermediate period, overcooling and overheating can be eliminated, which makes it possible to realize comfortable air conditioning.

In a fifth aspect of the present invention, the heat exchanger includes a heat transfer pipe, through which the heat-exchange water flows, and the heat transfer pipe has an ellipsoidal cross section. According to the fifth aspect of the present invention, the air flow resistance of the heat transfer pipe of the heat exchanger can be reduced by forming the heat transfer pipe such that the heat transfer pipe has an ellipsoidal shape. As a result, pressure loss in the air passing by the heat transfer pipe is reduced, and the area of contact between the heat transfer pipe and the fed air is increased, which makes it possible to improve heat exchange efficiency and energy-saving performance.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram showing an air-conditioning system.

FIG. 2 shows a heat exchanger.

FIG. 3 shows a table stored in a memory.

FIG. 4 is a flowchart showing the operation of the air-conditioning system.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 is a schematic diagram showing an air-conditioning system according to one embodiment of the present invention. The air-conditioning system 100 includes: air conditioners 1 each configured to cool down or heat up air for use in air conditioning (hereinafter, “air-conditioning air”) by means of water for use in heat exchange (hereinafter, “heat-exchange water”) to adjust an air supply temperature of the air-conditioning air, and supply the air-conditioning air to indoors; a heat source device 2 configured to adjust the temperature of the heat-exchange water, and selectively switch a setting water temperature of the heat-exchange water, to which the temperature of the heat-exchange water is to be adjusted, between a first setting water temperature preset corresponding to low exergy and a second setting water temperature preset corresponding to high exergy; a water circulating apparatus 4 configured to circulate the heat-exchange water between the heat source device 2 and the air conditioners 1; and a controller 5 configured to transmit a switching signal to the heat source device 2 to instruct the heat source device 2 regarding which one of the first setting water temperature and the second setting water temperature the setting water temperature of the heat-exchange water is to be switched to, and perform loading of a preset indoor temperature allowable range T1, a target water temperature difference S1, a setting elapsed time Z1, and a setting air supply temperature W1. The indoor temperature allowable range T1, the target water temperature difference S1, the setting elapsed time Z1, and the setting air supply temperature W1 are stored in a table (see FIG. 3) of a memory 50 connected to the controller 5. The meaning of the setting elapsed time Z1 will be described below. A user of the air-conditioning system 100 externally inputs a setting value T2 of an indoor temperature to the memory 50 via the controller 5.

Although the air-conditioning system 100 of FIG. 1 includes four air conditioners 1, the number of air conditioners 1 to be included is determined in accordance with the air conditioning capacity of the air-conditioning system 100.

Each air conditioner 1 includes: one heat exchanger 3 with a casing 70 through which the heat-exchange water flows; a water regulating valve 6 configured to increase and decrease the amount of heat-exchange water flowing through the heat exchanger 3 to adjust a temperature difference between the temperature of the heat-exchange water at the inlet side of the heat exchanger 3 and the temperature of the heat-exchange water at the outlet side of the heat exchanger 3 and adjust the air supply temperature of the air-conditioning air; and a fan 7 configured to take in the air-conditioning air into the casing 70 and supply the air-conditioning air to the outside of the casing 70 through the heat exchanger 3. As a result of the heat exchange in the heat exchanger 3, the air-conditioning air becomes cool air or warm air, and is then supplied to an indoor space to be air conditioned. It should be noted that a humidifier, filter, etc., may be provided inside the casing 70. In addition, the water regulating valve 6 may be provided outside the casing 70.

As shown in FIG. 2, the heat exchanger 3 is formed by attaching a serpentine heat transfer pipe 31 to a large number of heat exchanger plates 30. The heat exchanger plates 30 are spaced apart from each other such that the air-conditioning air is allowed to pass by the heat exchanger plates 30. The heat-exchange water flowing through the heat transfer pipe 31 exchanges heat with the air-conditioning air passing by the heat exchanger plates 30. Preferably, the heat transfer pipe 31 has an ellipsoidal cross section in order to make the air flow resistance of the heat transfer pipe 31 small. However, as an alternative, the heat transfer pipe 31 may have a round cross section.

The heat source device 2 cools down or heats up the heat-exchange water whose temperature has deviated from the first setting water temperature or the second setting water temperature as a result of absorbing heat from or releasing heat to the air-conditioning air in the heat exchanger 3 of the air conditioner 1, thereby adjusting the temperature of the heat-exchange water to the first setting water temperature or the second setting water temperature. The heat source device 2 concurrently performs temperature adjustment of the heat-exchange water that is cold water and temperature adjustment of the heat-exchange water that is hot water.

The water circulating apparatus 4 includes: a cold water circulation passage 8, through which the heat-exchange water that is cold water flows; a hot water circulation passage 9, through which the heat-exchange water that is hot water flows; water circulation passage switching mechanisms 10, each of which is configured to switch the heat-exchange water flowing through the heat exchanger 3 between the cold water and the hot water; and water feed pumps 11. These components are connected to each other by piping.

Each water circulation passage switching mechanism 10 connects a cold water forwarding portion of the cold water circulation passage 8, a hot water forwarding portion of the hot water circulation passage 9, and corresponding heat exchangers 3 via a first three-way switching valve 12 a. Each water circulation passage switching mechanism 10 also connects a cold water returning portion of the cold water circulation passage 8, a hot water returning portion of the hot water circulation passage 9, and the corresponding heat exchangers 3 via a second three-way switching valve 12 b. In FIG. 1, each water circulation passage switching mechanism 10 is provided for a plurality of (specifically two) air conditioners 1. However, as an alternative, the water circulation passage switching mechanism 10 may be provided for each air conditioner 1. In addition, although the circulation passage for the heat-exchange water has a four-pipe structure, through which the cold water and the hot water flow at the same time, the circulation passage for the heat-exchange water may alternatively have a two-pipe structure, in which the flow of the heat-exchange water is switched between the flow of the cold water and the flow of the hot water.

The controller 5 includes a microprocessor or the like, and is connected to a first detector 25 configured to detect the temperature of the heat-exchange water in a forward passage to the air conditioner 1, a second detector 26 configured to detect the temperature of the heat-exchange water in a return passage from the air conditioner 1, an indoor temperature detector 72 installed indoors, and an air supply temperature detector 71 provided at the outlet side of the casing 70. The first detector 25, the second detector 26, the indoor temperature detector 72, and the air supply temperature detector 71 are configured as sensors. In FIG. 1, only one of the air conditioners 1 is provided with the first detector 25, the second detector 26, and the air supply temperature detector 71. However, as an alternative, all or some of the air conditioners 1 may be provided with the first detector 25, the second detector 26, and the air supply temperature detector 71.

The controller 5 includes an arithmetic operation unit 13, a comparing unit 14, and a signal switching unit 15. The controller 5 also has a timer function of dividing its internal clock and measuring an elapsed time. The controller 5 receives an operation start/stop signal for the air-conditioning system 100, which is inputted by the user.

The arithmetic operation unit 13 calculates a water temperature difference between the temperature of the heat-exchange water detected by the first detector 25 and the temperature of the heat-exchange water detected by the second detector 26. The comparing unit 14 determines whether or not the indoor temperature detected by the indoor temperature detector 72 has reached the setting value T2. If the comparing unit 14 has determined that the indoor temperature is the setting value T2, the signal switching unit 15 outputs a switching signal to the heat source device 2 to instruct the heat source device 2 to switch the setting water temperature of the heat-exchange water to the first setting water temperature, and also operates and controls the water regulating valve 6 such that the water temperature difference calculated by the arithmetic operation unit 13 becomes less than or equal to the target water temperature difference S1. If the comparing unit 14 has determined that the indoor temperature is not the setting value T2, the signal switching unit 15 outputs a switching signal to the heat source device 2 to instruct the heat source device 2 to switch the setting water temperature of the heat-exchange water to the second setting water temperature, and also operates and controls the water regulating valve 6 such that the air supply temperature detected by the air supply temperature detector 71 reaches the setting air supply temperature W1. In addition, when the indoor temperature has deviated from the indoor temperature allowable range T1 after reaching the setting value T2, the signal switching unit 15 outputs a switching signal to the heat source device 2 to instruct the heat source device 2 to switch the setting water temperature of the heat-exchange water to the second setting water temperature, and then, when the indoor temperature has reached the setting value T2 again, the signal switching unit 15 starts counting an elapsed time. After the elapsed time has exceeded the setting elapsed time Z1, if the indoor temperature is still in the indoor temperature allowable range T1, the signal switching unit 15 outputs a switching signal to the heat source device 2 to instruct the heat source device 2 to switch the setting water temperature of the heat-exchange water to the first setting water temperature.

In a case where the heat-exchange water is cold water, the first setting water temperature is set to 9 to 11° C., and the second setting water temperature is set to 6 to 8° C. In a case where the heat-exchange water is hot water, settings are made as follows: the first setting water temperature is set to 34 to 36° C.; the second setting water temperature is set to 39 to 41° C.; the target water temperature difference S1 is set to 9 to 11° C.; the setting air supply temperature W1 is set to 13 to 16° C.; and the setting elapsed time Z1 is set to 20 to 40 minutes. In a case where the heat-exchange water is cold water, the indoor temperature allowable range T1 is a range between the indoor temperature setting value T2 and a value obtained by adding 1 to 2° C. to the setting value T2. In a case where the heat-exchange water is hot water, the indoor temperature allowable range T1 is a range between the indoor temperature setting value T2 and a value obtained by subtracting 1 to 2° C. from the setting value T2. Such adding or subtracting calculation for obtaining the indoor temperature allowable range T1 is performed by the arithmetic operation unit 13.

Usually, the target water temperature difference S1 is about 5° C. However, by setting the target water temperature difference S1 to a value that is about twice as great as the usual value, i.e., 9° C. to 11° C., the amount of heat exchange water flowing through the heat exchanger 3 can be substantially halved. This makes it possible to reduce the amount of energy consumed in the feeding of the heat-exchange water.

In addition, if the setting air supply temperature W1 is set to about 13° C. during cooling, the air supply volume is reduced than usual, and thereby the amount of energy consumed in the feeding of air can be reduced. It should be noted that these specific numerical values are merely non-limiting examples.

FIG. 4 is a flowchart showing the operation of the air-conditioning system 100. When a user inputs an operation start signal to the controller 5, the operation of the air-conditioning system 100 is started.

At the start of the operation of the air-conditioning system 100, the temperature to which the temperature of the heat-exchange water is to be adjusted by the heat source device 2 is set to the second setting water temperature (step S1). The comparing unit 14 of the controller 5 determines whether or not the indoor temperature detected by the indoor temperature detector 72 has reached the setting value T2 (step S2). If the indoor temperature has reached the setting value T2, the controller 5 resets the elapsed time to its initial value, and starts measuring the elapsed time (step S3). If the elapsed time has not yet reached the setting elapsed time Z1, the controller 5 determines whether or not the water temperature difference calculated by the arithmetic operation unit 13 is less than or equal to the target water temperature difference S1 (step S4, S6). If the calculated water temperature difference is greater than the target water temperature difference S1, the controller 5 operates and controls the water regulating valve 6 such that the calculated water temperature difference becomes less than or equal to the target water temperature difference S1 (step S7). This is the “first adjustment operation” of the present invention.

If the calculated water temperature difference is less than or equal to the target water temperature difference S1, the controller 5 determines whether or not an operation stop signal has been inputted by the user (step S8). If the operation stop signal has not been inputted yet, the controller 5 determines whether or not the indoor temperature detected by the indoor temperature detector 72 is in the indoor temperature allowable range T1 (step S9).

If the indoor temperature is out of the indoor temperature allowable range T1, the flow returns to step S1. If the indoor temperature is in the indoor temperature allowable range T1, the flow return to step S4, and the controller 5 waits for the elapsed time to exceed the setting elapsed time Z1. When the elapsed time has exceeded the setting elapsed time Z1, if the state where the indoor temperature is in the indoor temperature allowable range T1 is still maintained, then it is estimated that the air-conditioning load is stable. Accordingly, the controller 5 outputs a switching signal to the heat source device 2 to instruct the heat source device 2 to switch the setting water temperature of the heat-exchange water to the first setting water temperature (step S5). In this manner, a phenomenon in which the setting water temperature of the heat-exchange water is switched frequently can be prevented while the heat source device 2 is in operation, thereby making it possible to improve the reliability and stability of the heat source device 2. It should be noted that the determination in step S8 as to whether or not an operation stop signal has been inputted may be performed at any timing in the flowchart of FIG. 4.

If it is determined in step S2 that the indoor temperature deviates from the setting value T2, the controller 5 determines whether or not the air supply temperature has reached the setting air supply temperature W1 in a state where the temperature to which the temperature of the heat-exchange water is to be adjusted is set to the second setting water temperature (step S10). If it is determined that the air supply temperature deviates from the setting air supply temperature W1, the controller 5 operates and controls the water regulating valve 6 such that the air supply temperature becomes the setting air supply temperature W1 (step S11). This is the “second adjustment operation” of the present invention.

When the air supply temperature reaches the setting air supply temperature W1, the flow returns to step S1, and in a state where a switching signal instructing the heat source device 2 to switch the setting water temperature of the heat-exchange water to the second setting water temperature is outputted to the heat source device 2, the control operation is performed until the indoor temperature reaches the setting value T2.

The air-conditioning system 100 according to the present embodiment provides advantageous effects as described below. When the indoor temperature is the setting value T2, by adjusting the temperature difference between the temperature of the heat-exchange water at the inlet side of the heat exchanger 3 and the temperature of the heat-exchange water at the outlet side of the heat exchanger 3 to the target water temperature difference S1, quick cooling, quick heating, or the like of the heat-exchange water can be prevented, and thereby wasteful energy consumption can be reduced.

When the indoor temperature is not the setting value T2, the temperature to which the temperature of the heat-exchange water is to be adjusted is set to the second setting water temperature in preparation for an increase in air-conditioning load. In this manner, while keeping a variation in the indoor temperature to a minimum, cooling or heating is performed quickly until the air supply temperature of the air-conditioning air becomes the setting air supply temperature W1. This makes it possible to perform air conditioning with excellent stability and comfortableness.

The present invention is not limited to the above-described embodiment. For example, the air-conditioning air taken into the air conditioner 1 may be any of the following: outside air (outdoor air); return air (indoor air); and mixed air of the outside air and the return air. Although the above-described embodiment gives an example in which the single controller 5 collectively controls the plurality of air conditioners 1, the controller 5 may be provided for each air conditioner 1.

As this invention may be embodied in several forms without departing from the spirit of essential characteristics thereof, the present embodiment is therefore illustrative and not restrictive, since the scope of the invention is defined by the appended claims rather than by the description preceding them, and all changes that fall within metes and bounds of the claims, or equivalence of such metes and bounds thereof are therefore intended to be embraced by the claims.

DESCRIPTION OF THE REFERENCE CHARACTERS

-   1 air conditioner -   2 heat source device -   3 heat exchanger -   4 water circulating apparatus -   5 controller -   6 water regulating valve -   8 cold water circulation passage -   9 hot water circulation passage -   100 air-conditioning system 

What is claimed is:
 1. An air-conditioning system comprising: an air conditioner configured to adjust an air supply temperature of air-conditioning air by using heat-exchange water, and supply the air-conditioning air to indoors; a heat source device configured to adjust a temperature of the heat-exchange water, and selectively switch a setting water temperature of the heat-exchange water, to which the temperature of the heat-exchange water is to be adjusted, between a first setting water temperature preset corresponding to low exergy and a second setting water temperature preset corresponding to high exergy; and a controller configured to transmit a switching signal to the heat source device to instruct the heat source device regarding which one of the first setting water temperature and the second setting water temperature the setting water temperature of the heat-exchange water is to be switched to, and perform loading of a preset indoor temperature allowable range, a target water temperature difference, a setting value of an indoor temperature, and a setting air supply temperature, wherein the air conditioner includes: a heat exchanger, through which the heat-exchange water flows; and a water regulating valve configured to increase and decrease an amount of heat-exchange water flowing through the heat exchanger to adjust a temperature difference between a temperature of the heat-exchange water at an inlet side of the heat exchanger and a temperature of the heat-exchange water at an outlet side of the heat exchanger and adjust the air supply temperature of the air-conditioning air, the controller performs a first adjustment operation in a case where the indoor temperature is the setting value, the first adjustment operation including: transmitting a switching signal to the heat source device to instruct the heat source device to switch the setting water temperature of the heat-exchange water to the first setting water temperature; and operating and controlling the water regulating valve to adjust the temperature difference between the temperature of the heat-exchange water at the inlet side of the heat exchanger and the temperature of the heat-exchange water at the outlet side of the heat exchanger to the target water temperature difference, and the controller performs a second adjustment operation in a case where the indoor temperature is not the setting value, the second adjustment operation including: transmitting a switching signal to the heat source device to instruct the heat source device to switch the setting water temperature of the heat-exchange water to the second setting water temperature; and operating and controlling the water regulating valve to adjust the air supply temperature of the air-conditioning air to the setting air supply temperature.
 2. The air-conditioning system according to claim 1, wherein in a case where the indoor temperature deviates from the indoor temperature allowable range, the controller outputs a switching signal to the heat source device to instruct the heat source device to switch the setting water temperature of the heat-exchange water to the second setting water temperature, and when a setting elapsed time has passed after the indoor temperature reaches the setting value, if a state where the indoor temperature is in the indoor temperature allowable range is maintained, the controller outputs a switching signal to the heat source device to instruct the heat source device to switch the setting water temperature of the heat-exchange water to the first setting water temperature.
 3. The air-conditioning system according to claim 1, wherein in a case where the heat-exchange water is cold water, the first setting water temperature is set to 9 to 11° C., and the second setting water temperature is set to 6 to 8° C., and in a case where the heat-exchange water is hot water, the first setting water temperature is set to 34 to 36° C., the second setting water temperature is set to 39 to 41° C., and the target water temperature difference is set to 9 to 11° C.
 4. The air-conditioning system according to claim 1, comprising a water circulating apparatus configured to circulate the heat-exchange water between the heat source device and the heat exchanger, wherein the water circulating apparatus includes: a cold water circulation passage, through which the heat-exchange water that is cold water flows; a hot water circulation passage, through which the heat-exchange water that is hot water flows; and a water circulation passage switching mechanism configured to connect the cold water circulation passage, the hot water circulation passage, and the heat exchanger, and switch the heat-exchange water flowing through the heat exchanger between the cold water and the hot water.
 5. The air-conditioning system according to claim 1, wherein the heat exchanger includes a heat transfer pipe, through which the heat-exchange water flows, and the heat transfer pipe has an ellipsoidal cross section.
 6. The air-conditioning system according to claim 2, wherein in a case where the heat-exchange water is cold water, the first setting water temperature is set to 9 to 11° C., and the second setting water temperature is set to 6 to 8° C., and in a case where the heat-exchange water is hot water, the first setting water temperature is set to 34 to 36° C., the second setting water temperature is set to 39 to 1° C., and the target water temperature difference is set to 9 to 11° C.
 7. The air-conditioning system according to claim 2, comprising a water circulating apparatus configured to circulate the heat-exchange water between the heat source device and the heat exchanger, wherein the water circulating apparatus includes: a cold water circulation passage, through which the heat-exchange water that is cold water flows; a hot water circulation passage, through which the heat-exchange water that is hot water flows; and a water circulation passage switching mechanism configured to connect the cold water circulation passage, the hot water circulation passage, and the heat exchanger, and switch the heat-exchange water flowing through the heat exchanger between the cold water and the hot water.
 8. The air-conditioning system according to claim 2, wherein the heat exchanger includes a heat transfer pipe, through which the heat-exchange water flows, and the heat transfer pipe has an ellipsoidal cross section. 